Many formulas have been developed to model the flow of fluids.  The Hazen-Williams formula has been a popular method of estimating the head loss in piping systems for many years (particularly prior to the availability of today’s modern computers).  However, this empirical formula will only give reasonable accuracy if the fluid is water at 60oF or similar.


The Colebrook-White formula may be used with confidence to calculate an accurate friction factor applicable to the turbulent flow of fluids. The Colebrook-White formula is applicable over a whole range of fluid densities and viscosities, provided that the fluid flow is turbulent.


The Pipe Flow Wizard software uses the Colebrook-White friction factor with the Darcy-Weisbach equation when calculating friction loss for non-compressible flow (liquids). The Colebrook-White friction factor is also used with some compressible gas flow equations such as the General Fundamental Flow equation.